U.S. Pat. No. 673,583 describes a transport system which comprises rail bogies of the kind having two axles and a central bogie bolster arranged between the axles and transverse to the intended direction of travel and semi-trailers which are preferably of the kind having road wheels at the trailing ends and adapted for connection at their leading ends to a tractor unit. The rail bogie bolster has a pocket in which a mounting member is held, the pocket and mounting member having complementary surfaces in engagement to permit limited movement of the mounting member relative to the pocket. The mounting member is adpated for releaseable attachment to the frame of a semi-trailer which at one end is provided with means for receiving the attachment of the mounting member and which at the other end is connectable to a similar semi-trailer so that a train may be constructed of semi-trailers and bogies with each bogie effectively supporting the weight of one semi-trailer. In this arrangement, one semi-trailer is movable relative to an adjacent semi-trailer about a first substantially vertical axis and the semi-trailer is pivotable relative to the bogie about a second substantially vertical axis. These vertical axes preferably coincide or substantially coincide so as to provide a considerable reduction in overthrow and diagonal racking loads as the semi-trailer negotiates a bend. The semi-trailers can readily be converted to a road mode.
Reference is directed to the aforesaid patent specification for further details of the transport system.
A train may be constructed from a plurality of the semi-trailers each of which is releasably mounted on one of the rail bogies and, as indicated, with the exception of the first and last semi-trailers, the weight of one semi-trailer is effectively supported by one rail bogie.
In order to terminate the train it is either necessary to adapt the last semi-trailer to receive the bogie by fitting a front bolster or by adapting a front bolster to receive attachment means on the bogie. This, however, may be undesirable, due to the expense involved, and it may, therefore, be preferred to provide each train with a special adapter bogie whereby the train may be connected to an engine. For reverse running a coupling member may be provided in the form of a triangular frame terminating in cups for receiving the buffers of an engine and having a tongue for coupling in the socket of a semi-trailer.
While, as described in the aforesaid patent specification, no problems arise in making up a train consisting entirely of the bogies and semi-trailers it is apparent that problems will arise if it is attempted to incorporate these units of the transport system in conventional freight trains, as several of the adapter bogies will be required, which is uneconomic. Furthermore, due to the necessity of adequately transferring the normal buff and draught loads between units of the train, the described triangular coupling members are not suitable for coupling the bogie and semi-trailer units of the transport system in freight trains including conventional rail cars.